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Physics 101 SFSU Newton Einstein Physics 101: Concepts in Physics Physics 101 SFSU Course Objectives 1. Explore the approaches that physics brings to understand the world around us: – – – – Reductionism Scientific Method Empiricism & Skepticism Quantitative Models 2 Physics 101 SFSU Course Objectives, continued 2. Appreciate the influence physics has on us all – Begin to see physics in the world around you – Develop your natural intuition, stimulate curiosity – Think into the unknown (ooh that’s scary!) 3. Understand basic laws of physics – Newton’s laws of motion, gravitation (even relativity) – Concepts of mass, force, acceleration, energy, momentum, power, etc. – Electromagnetism – Quantum Mechanics – Light and optics 3 Physics 101 SFSU Course Objectives, continued 4. Map out the hierarchy of the Universe – The cosmos • • • – The microcosmos • • 5. Molecules, compounds, atoms Subatomic particles, fundamental forces Exposing the limits of our understanding – – 6. Earth, Moon, Sun, Solar system Stars, our Galaxy, other galaxies Cosmological scales: clustering, accelerating Universe Complexity: chaos, biological systems, economics Unification schemes: string theory, supersymmetry Enhance your scientific literacy – – know the difference between science and the supernatural feel encouraged to read popular science articles/books 4 Physics 101 SFSU Topics to be Covered • • • • • • • • What constitutes physics The BIG picture: macro- and micro-cosmos Newton’s laws of motion, energy, momentum, etc. Gravity and Relativity: from Newton to Einstein Electromagnetism and Light Quantum Mechanics and associated weirdness The frontiers of physics The role of physics in our society 5 Physics 101 SFSU How Much !? • This course will largely focus on qualitative, conceptual content • That does not mean the ideas are trivial! • We will be using • • • • Simple graphs Occasional basic algebra Averages Power of 10 6 SFSU Units of Length, Mass, and Time Physics 101 7 SFSU Units of Length, Mass, and Time Physics 101 8 SFSU Units of Length, Mass, and Time Physics 101 9 Physics 101 SFSU Expectations • Attend lectures • Participate! – If it doesn’t make sense, ask! Everyone learns that way. – Don’t be bashful about answering questions posed. – In-class voting system should make this fun • Do the work: – It’s the only way this stuff will really sink in – exams become easier • Explore, think, ask, speculate, admire, enjoy! – Physics can be fun, enriching, beautiful 10 Physics 101 SFSU What Is Science? • Which of the following best describes “science”? – – – – – – A compendium of answers A set of rules about the natural world A methodology Exploration, curiosity; a compendium of questions Observation, experimentation Boring guys in white coats with nerdy senses of humor • Science has bits of all these (esp. middle four) 11 Physics 101 SFSU Science = A Process for Change! • • • • • • Discovery Experiment/Observation Hypothesis Prediction Test Theory An ongoing cycle – the “scientific method” Scientific Method: The dynamic interplay between theory and experiment 12 Physics 101 SFSU Science also brings an Attitude Scientists must accept their experimental findings even when they would like them to be different. They must strive to distinguish between what they see and what they wish to see, for scientists, like most people, have a vast capacity for fooling themselves. People have always tended to adopt general rules, beliefs, creeds, ideas, and hypotheses without thoroughly questioning their validity and to retain them long after they have been shown to be meaningless, false, or at least questionable. The most widespread assumptions are often the least questioned. Most often, when an idea is adopted, particular attention is given to cases that seem to support it, while cases that seem to refute it are distorted, belittled, or ignored. 13 Physics 101 SFSU What is “Physics” • An attempt to rationalize the observed Universe in terms of irreducible basic constituents, interacting via basic forces. • An evolving set of (sometimes contradictory!) organizing principles, theories, that are subjected to experimental tests. • This has been going on for a long time.... with considerable success 14 Physics 101 SFSU Reductionism • Attempt to find unifying principles and properties e.g., gravitation: Kepler’s laws of planetary motion Falling apples Universal Gravitation “Unification” of forces 15 Physics 101 SFSU Reductionism, continued All the stuff you see around you Chemical compounds Elements (Atoms) e,n,p Superstrings? Many thousands Many hundreds Tens 3 An ongoing attempt to deduce the basic building blocks 16 Physics 101 SFSU An Evolving World View • As our understanding grows, theories are supplanted (or subsumed) Kepler’s laws of planetary motion Falling apples Universal General Gravitation Relativity 17 Physics 101 SFSU Should we even pay attention, then? • Science is always on the move – theories that long stood up to experiment are shot down • But usually old theory is good enough to describe all experiments predating the new trouble-making experiment – otherwise it would never have been adopted as a theory • Ever higher precision pushes incomplete theories to their breaking points • Result is enhanced understanding – deeper appreciation/insight 18 Physics 101 SFSU Mathematics: the natural language of Physics Engineering Biology Geology Chemistry Astronomy Physical Reality Abstraction Our Universe 19 Physics 101 SFSU Subdisciplines of Physics • • • • • • • • Astrophysics Condensed matter physics Atomic/Optical Physics Nuclear Physics Particle Physics Plasma Physics Biophysics .... Experimental vs. Theoretical 20 Physics 101 SFSU Mapping the Intellectual Frontier • One (but by no means the only) way to organize our ignorance is in terms of length scales • Our intuition and everyday experience spans only a very small range of this scale Really small Subatomic Particles “ordinary” you Really big Observable Universe 21